Crouching in a state-of-the-art bunker located under an abandoned barn, a man breathes deeply. All around him lights are flashing on and generators are powering up.

Bang.

The sound comes from the other side of the 15-inch thick steel door. One of Them.

Above the bunker, a rabies outbreak has mutated into a deadly worldwide infection that attacks the very essence of being human, leaving only the most primitive desire: to feed.

Against this onslaught, there is one defense - Bunker Z.